ERA5 almanac — 8 years of real data

Kauai in March

Kauai in March: 90% of days see measurable rain, 69°F average high, 2% of days historically clear (n=248, ERA5 2018–2025).

Kauai in March is historically a poor month for sun: only 2% of days clear across 8 years (n=248, avg high 69°F). January is the clearest month for Kauai historically. Historical average, not a forecast.

What you are reading: 8-year historical averages from the ERA5 reanalysis, not a forecast. A month that is historically 90% clear can still be overcast on your specific trip. For this week’s actual forecast, see the live Kauai page. Both can be true at once: “historically strong in this month; this particular week is not.” We label which is which.

Early vs. Late March

Clear-sky percentage for Kauai in March, split by half-month. “n” is the number of days sampled across 8 years (2018–2025).
Period	% Clear days	Sample (n)	Avg high
Early March 1st–15th	2%	n=120	69°F
Late March 16th–end	2%	n=128	69°F
Full month average	2%	n=248	69°F

Sunshine & warmth in March

A second measure using actual sunshine hours (ERA5 sunshine_duration), not the daily weather code. A Lowcountry day with 12 hours of sun and a 25-minute afternoon storm is counted below as a warm, sunny day — because it was. How we define this.

Sunshine-based metrics for Kauai in March. Primary: % of days ≥ 72°F with > 6 h of sunshine.
Period	Warm & sunny (≥72°F, >6 h sun)	Sample (n)
Early March 1st–15th	17%	n=120
Late March 16th–end	34%	n=128
Full month average	26%	n=248

11.1 h median sunshine per day 82% of days exceed 8 h sunshine 90% of days see ≥ 1 mm rain — rain is not hidden

Comparison (old vs new): WMO-code “clear” bar: 2%. Sunshine-based “warm & sunny”: 26%. The 24-point gap is from brief afternoon convective storms that stamp the whole day as “rain” in the WMO code but leave the bulk of the sunshine untouched.

Bottom line

Kauai is historically almost never clear in March: only 2% of days meet the clear bar across 8 years (n=248). Come back in January if you want clear skies here. Plan entirely around indoor or overcast-friendly activities.

→ See all destinations in January — historically the best month for sun in Kauai.

Every month in Kauai

Compare across all months with data. Numbers are historical clear-sky %.

Historical clear-sky % for Kauai, all months, ERA5 2018–2025.
Month	% Clear	Sample (n)
January	5%	n=248	All destinations →
February	2%	n=226	All destinations →
March ← this page	2%	n=248	All destinations →
April	1%	n=240	All destinations →
May	0%	n=248	All destinations →
June	2%	n=240	All destinations →
July	0%	n=248	All destinations →
August	0%	n=248	All destinations →
September	0%	n=240	All destinations →
October	1%	n=248	All destinations →
November	2%	n=240	All destinations →
December	4%	n=248	All destinations →

Frequently asked

Does it rain in Kauai in March?

Yes, frequently. In Kauai, 90% of days in March see measurable rain, based on 8 years of ERA5 historical data (n=248 days, 2018–2025). This is a historical average, not a forecast.

Is Kauai good for sun in March?

Not usually. Kauai is historically overcast in March: only 2% of days are clear (avg high 69°F, n=248 days, ERA5 2018–2025). January is historically far better for sun here.

→ Kauai live forecast — this week’s actual 7-day weather, not historical
→ Best destinations in March — all destinations ranked by March clear-sky %
→ All destinations
→ Raw data (JSON) — buckets, n, source

All percentages are historical averages from the ERA5 reanalysis via Open-Meteo, 8 full years (2018–2025). “Clear” means avg high ≥ 72 °F, precipitation < 1 mm, and a non-precipitation weather code. This is history, not a forecast. The live 7-day outlook for any destination is on its own page and may differ from the long-run average. Data from Open-Meteo.